Capsule medical apparatus and body-cavity observation method

ABSTRACT

Provided is a capsule medical apparatus including a capsule body, a control member, and an observing member. The capsule body is to be introduced into a lumen of a subject. The control member controls a movement of the capsule body in the lumen by a flow of a fluid introduced in the lumen. The observing member is fixed inside the capsule body and observes a direction of the flow of the fluid and a direction different from the flow of the fluid according to the movement of the capsule body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capsule medical apparatus such as acapsule endoscope for traveling in a lumen with a liquid such as water,which is introduced into a subject, to observe inside the lumen and abody-cavity observation method.

2. Description of the Related Art

Recently, in a field of endoscopes, a capsule endoscope having animaging function and a radio communication function has been appearing.This capsule endoscope includes a structure for displacing along withperistaltic movement in an internal organ (in a lumen) such as theesophagus, stomach and small intestine and sequentially taking imageswith its imaging function until it is naturally discharged from the bodyof the subject, after swallowed by the subject through his or her mouthfor the observation (examination).

WO 02/95351 discloses a technique suited for observing the largeintestine, in which the specific gravity of the capsule endoscope is setas same as that of the liquid therearound or 1 which is same as that ofwater so that, when a subject swallows the capsule endoscope with theliquid, the capsule endoscope floats in the liquid and travels quicklyin the body-cavity to the large intestine. When the capsule endoscope isattached to the wall surface of the body-cavity, only close narrow areais imaged; however, according to WO 02/95351, since the capsuleendoscope floats in the liquid to observe, an observing field ismaintained and every part can be observed.

Regarding observations of inside hollow organs such as the largeintestine with the use of such a capsule endoscope, an entire of thelumen may be needed to be observed in some cases and a particularportion such as a polyp (lumen wall) may be needed to be observed inother cases. In order to meet such demands, for example, WO 03/11103discloses a capsule endoscope having at least one illumination source,at least one imaging sensor, and at least two optic systems. Further, WO02/54932 discloses a capsule endoscope having at least one imagingdevice and an optic system including a plurality of optical paths.According to WO 03/11103 and WO 02/54932, the capsule endoscope iscapable of imaging the lumen not only in the axial direction of thelumen but also in an inner wall direction of the lumen in the holloworgan.

However, according to the capsule endoscope of WO 03/11103 and WO02/54932, the system depends on the structure of the imaging opticalsystem in the capsule endoscope and in order to optimize imagingdirection to perform a proper observation in the lumen in its axialdirection and the inner wall direction, more optic systems or opticalpaths are required to be set. Thus, the structure becomes more complexand enlarged so that the proper size of the capsule endoscope to beintroduced into a subject cannot be maintained.

SUMMARY OF THE INVENTION

A capsule medical apparatus according to one aspect of the presentinvention includes a capsule body to be introduced into a lumen of asubject; a control member controlling a movement of the capsule body inthe lumen by a flow of a fluid introduced in the lumen; and an observingmember fixed inside the capsule body and observing a direction of theflow of the fluid and a direction different from the flow of the fluidaccording to the movement of the capsule body.

A body-cavity observation method according to another aspect of thepresent invention includes the steps of: ingesting a capsule medicalapparatus; ingesting a fluid having a specific gravity which issubstantially same as that of the capsule medical apparatus;controlling, by the capsule medical apparatus, movement in a lumen by aflow of the fluid; observing, by the capsule medical apparatus, adirection of the flow of the fluid; and observing, by the capsulemedical apparatus, a direction different from the direction of the flowof the fluid.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a use example of a capsuleendoscope according to a first embodiment of the present invention;

FIG. 2 is a schematic block diagram showing a use example of a capsuleendoscope according to a first modification;

FIG. 3 is a schematic block diagram showing a use example of a capsuleendoscope according to a second modification;

FIG. 4 is a schematic rear view of the capsule endoscope;

FIG. 5 is a schematic perspective view showing the capsule endoscopeaccording to a second embodiment of the present invention;

FIG. 6 is a rear view of the capsule endoscope in FIG. 5;

FIGS. 7A, 7B and 7C are schematic block diagrams showing a use exampleof the capsule endoscope;

FIG. 8 is a schematic block diagram showing a use example of a capsuleendoscope according to a third modification;

FIG. 9 is a schematic block diagram showing a use example of a capsuleendoscope according to a fourth modification;

FIG. 10 is a schematic block diagram showing a use example of a capsuleendoscope according to a fifth modification;

FIG. 11 is a rear view of the capsule endoscope in FIG. 10;

FIG. 12 is a schematic block diagram showing a use example of a capsuleendoscope according to a sixth modification;

FIG. 13 is a rear view of the capsule endoscope in FIG. 12; and

FIGS. 14A, 14B and 14C are schematic block diagrams showing a useexample of a capsule endoscope according to a seventh modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of a capsule medical apparatus and a body-cavity observationmethod according to the present invention will be described withreference to the drawings. The embodiments describe examples of thepresent invention applied to a capsule endoscope as a capsule medicalapparatus. It will be appreciated that the present invention is notlimited to the following embodiments and can be implemented withmodifications within the spirit of the present invention.

FIG. 1 is a schematic block diagram showing a use example of a capsuleendoscope according to a first embodiment of the present invention. Thecapsule endoscope 10 of the first embodiment includes a capsule body 20insertable into a lumen of a subject 1 to be tested, an observing member30 installed in the capsule body 20, other installed elements such as aradio transmission unit, a battery, an image processing unit, which arenot shown, and a rotary guide member 40 disposed on outer face of thecapsule body 20.

The capsule body 20 is made in a size capable of being swallowed by thesubject 1 through his or her mouth into a body cavity of the subject 1.The capsule body 20 is formed in a domed capsule shape, in which ends ofhemispherical domes are integrated by a cylindrical member therebetweenand the direction connecting the ends of the hemispherical domesrepresents a longitudinal direction.

Here, the capsule endoscope 10 of the first embodiment is configured topropel in the lumen 2 of the subject 1, for example, the largeintestine, as floating in a fluid 3 that is introduced in the lumen 2.The capsule body 20, which includes installed elements such as theobserving member 30, is configured to have a specific gravity that issubstantially one with respect to the fluid 3, substantially the same asthe fluid 3. The fluid 3 is a fluid, which is capable of being swallowedby the subject 1 through his or her mouth and is clear to the wavelengthof a light source used by the observing member 30 for imaging. In thefirst embodiment, drinkable water having specific gravity close to oneis used as an example of the fluid 3. A gravity center G of the capsulebody 20 containing the observing member 30 and other elements is set asthe center of the capsule body 20 (the center on the longitudinal axis Lpassing through the center of the cylinder).

Further, the observing member 30 is an imaging member for imaging animage of the inside of the lumen and, according to the fist embodiment,is composed of fist and second imaging members 31, 32 which are fixed ata position one-sided with respect to the longitudinal axial direction inthe capsule body 20. The first imaging member 31, which is not shown,includes a light source for illuminating an imaging region, asolid-state imaging device such as CCD or CMOS imager for receivingcatoptric light from the imaging region generated by the illuminatinglight of the light source to image the inside of the lumen, and animaging optic system such as an imaging lens for producing an opticalimage of the imaging region to the solid-state imaging device. As shownwith dashed lines in FIG. 1, the first imaging member 31 is disposed soas to provide an imaging field in the longitudinal axial direction ofthe capsule body 20. Further, the second imaging member 32, which is notshown, includes a light source for illuminating an imaging region, asolid-state imaging device such as CCD or CMOS imager for receivingcatoptric light from the imaging region generated by the illuminatinglight of the light source to image the inside of the lumen, and animaging optic system such as an imaging lens for producing an opticalimage of the imaging region to the solid-state imaging device. As shownwith the dashed lines in FIG. 1, the second imaging member 32 isdisposed so as to provide an imaging field in a direction oblique to thelongitudinal axis direction of the capsule body 20. Here, the firstimaging member 31 is set to be a far focus to focus on a distant pointand the second imaging member 32 is set to be a near focus to focus on aclose point. The imaging field of the second imaging member 32 may be ina horizontal direction with respect to the vertical axial direction ofthe capsule body 20. Here, the capsule body 20 includes a member havingclearness or translucency at least at regions corresponding to theimaging fields of the first and second imaging members 31, 32.

Further, the rotary guide member 40 is configured to work as a controlmember for controlling movement of the capsule body 20 in the lumen 2,which is moved by the flow of the fluid 3 introduced into the lumen 2.According to the first embodiment, the rotary guide member 40 isconfigured to rotate the capsule body 20 with the flow of the fluid 3about the longitudinal axis of the capsule body 20 in a circumferentialdirection. The rotary guide member 40 is composed of a spiral memberformed of a continuous projection 41 with projection amount which iscapable of interfering the flow of the fluid 3, spirally formed aroundthe outer surface of the capsule body 20. The cross-sectional shape ofthe projection 41 may be formed in a hemicycle or a rectangle shape.Further, the interval of the spiral, the number of the spiral, the angleof the spiral or the like of the projection 41 can be set arbitrarily.

An image processing unit which is installed in the capsule body 20,which is not shown, provides necessary processing on the images of theinside of the lumen taken by the first and second imaging members 31,32. A radio transmission unit, which is not shown, radio-outputs lumenimage data which has been subjected to necessary processing by the imageprocessing unit to a receiver (not shown) or the like disposed outsidethe subject 1. A battery, which is not shown, supplies necessary powerto an electrical drive unit such as the light source or solid-stateimaging device in the capsule body 20.

Next, an observation of inside of the lumen 2, for example, the largeintestine, with the use of the capsule endoscope 10 of the firstembodiment will be described. Basically, the capsule endoscope 10 andthe fluid 3 are swallowed by the subject 1 to substantially fill thelumen 2 such as the large intestine as an observed portion in thesubject 1 with the fluid 3 so that the capsule endoscope 10 travels asfloating in the fluid 3. Then the inside image of the lumen is taken bythe first and second imaging members 31, 32 to observe the lumen. Thecapsule endoscope 10 and the liquid 3 may be swallowed at the same timeor may be swallowed in any order.

Here, as shown by arrows in FIG. 1, the fluid 3 introduced in the lumen2 flows along the axis of the lumen 2 toward an exit of the lumen. Whenthe capsule endoscope 10 is in such a flow of the fluid 3, since thecapsule body 20 has the rotary guide member 40 of the spirally formedprojection 41 on the outer face and the rotary guide member 40interferes the flow of the fluid 3, the capsule endoscope 10 iscontrolled to move along the flow as rotating in the circumferentialdirection about the longitudinal axis L. The first and second imagingmembers 31, 32 take images inside the lumen 2 in such movements of thecapsule body 20. In other words, the first imaging member 31 takesimages of the lumen 2, as rotating, in front (or back) in the axialdirection that is the direction of the flow of the fluid 3. The secondimaging member 32 sequentially takes images of an internal surface 2 aof the lumen 2, which is located in different direction from the flow ofthe fluid 3, as moving around therein. Further, since the focus positionof the first imaging member 31, which images the lumen 2 in the axialdirection, is set at a long distance, a far focused and fine image ofthe inside of the entire lumen can be obtained. Since the focus positionof the second imaging member 32, which images the internal surface 2 aas moving around therein, is set at a short distance, a near focused andfine internal surface image can be obtained and a particular portionsuch as a polyp 2 b can surely be observed.

As described above, according to the capsule endoscope 10 of the firstembodiment, the observing fields in the lumen 2 can be dynamicallychanged to be optimized by controlling the capsule body 20 to move asrotating in a circumferential direction with the use of the flow of thefluid 3. With this structure, the entire parts in the lumen 2 can surelybe observed without complicating the structure of an observing member(imaging member), which is to be installed in the capsule body 20.Further, according to the capsule endoscope 10 of the first embodiment,the gravity center G is set at the substantially center of the capsulebody 20 and the specific gravity with respect to the fluid 3 is set assubstantially one. Accordingly, the capsule body 20 is in a mobile stateand rotatable smoothly in the circumferential direction when the rotaryguide member 40 interferes the flow of the fluid 3. With this structure,the above described observing operation can be certainly performed.

FIG. 2 is a schematic block diagram showing a use example of the capsuleendoscope according to a first modification. According to a capsuleendoscope 11 of the first modification, a rotary guide member 42 isformed with a plurality of noncontiguous projections 43 so as to form anintermissive spiral shape. In this way, the rotary guide member 42 maybe formed in an intermissive spiral shape with the noncontiguousprojections 43 if the rotary guide member 42 is configured to interfacethe flow of the fluid 3 to rotate the capsule body 20 in acircumferential direction about the longitudinal axis L. Such a rotaryguide member 42 may be formed more easily than the rotary guide memberof the continuous projection 41.

The rotary guide member is not limited to what is formed spirally withthe projections 41, 43 and may be, for example, formed with a recess,which is spirally formed on the outer surface of the capsule body 20 tointerface the flow of the fluid 3. Further, according to the firstembodiment and the first modification, the observing member 30 (thefirst and second imaging members 31, 32) is not limited to be disposedonly at one end in the capsule body 20 and the observing members 30 maybe fixed at both ends as a compound-eye-type structure. In addition, thefirst imaging member 31 and the second imaging member 32 may be arrangedat different ends.

FIG. 3 is a schematic block diagram showing a use example of a capsuleendoscope according to a second modification and FIG. 4 is a schematicrear view of the capsule endoscope. A capsule endoscope 12 according tothe second modification includes a propeller 44 as a rotary guide member45, which is integrally provided on the outer surface of a rear portion(the portion where the observing member 30 is not provided) of thecapsule body 20. When the capsule endoscope 12 having such structurereceives a flow of the fluid 3 in the lumen 2, the propeller 44 as therotary guide member 45 rotates as interfering the flow of the fluid 3 sothat the capsule body 20 moves forward in the lumen 2 as rotating,together with the propeller 44, in a circumferential direction about thelongitudinal axis L. Accordingly, same as the case of the firstembodiment, the inside of the lumen 2 may surely be observed.

Next, a capsule endoscope according to a second embodiment of thepresent invention will be described. FIG. 5 is a schematic perspectiveview showing the capsule endoscope according to the second embodiment,FIG. 6 is a rear view of the capsule endoscope in FIG. 5, and FIGS. 7A,7B and 7C are schematic block diagrams showing a use example of thecapsule endoscope. A capsule endoscope 50 according to the secondembodiment includes a capsule body 60 which is insertable into a lumenof a subject 1, an observing member 70 installed in the capsule body 60,other installed elements, which are not shown, such as a radiotransmission unit, a battery or an image processing unit, and a rotaryguide member 80 disposed on the outer surface of the capsule body 70.

The capsule body 60 is basically same as the capsule body 20. Thecapsule body 60 is made in a size capable of being swallowed by thesubject 1 through his or her mouth into a cavity. The capsule body 60 isformed in a domed capsule shape, in which ends of hemispherical domesare integrated by a cylindrical member therebetween and the directionconnecting the ends of the hemispherical domes is a longitudinaldirection.

Here, the capsule endoscope 50 of the second embodiment moves in a lumen2, for example, the large intestine of the subject 1, as floating in thefluid 3 introduced into the lumen 2. The capsule body 60, which includeselements such as the observing member 70 therein, is configured to havea specific gravity that is substantially one with respect to the fluid3, substantially the same as that of the fluid 3. The fluid 3 is aliquid, which is capable of being swallowed by the subject 1 through hisor her mouth and is clear to the wavelength of a light source used bythe observing member 30 for imaging. In the second embodiment, drinkablewater having specific gravity close to one is used as an example of thefluid 3. The gravity center G of the capsule body 60 containing theobserving member 30 and other elements is set as the center of thecapsule body 60 (the center on the longitudinal axis L passing throughthe center of the cylinder).

Further, the observing member 70 is an imaging member for imaging animage of the inside of the lumen and, according to the secondembodiment, is composed of an imaging member 71 that is fixed at aposition one-sided with respect to the longitudinal axial direction inthe capsule body 60. The imaging member 71, which is not shown, includesa light source for illuminating an imaging region, a solid-state imagingdevice such as CCD or CMOS imager for receiving catoptric light from theimaging region generated by the illuminating light of the light sourceto image the inside of the lumen, and an imaging optical system such asan imaging lens for producing an optical image of the imaging region tothe solid-state imaging device. As shown with dashed lines in FIGS. 7Ato 7C, the imaging member 71 is disposed so as to provide an imagingfield in the longitudinal axial direction of the capsule body 60. Here,the capsule body 60 includes a member having clearness or translucencyat least at regions corresponding to the imaging field of the imagingmember 71.

Further, the rotary guide member 80 is configured to work as a controlmember for controlling movement of the capsule body 20 in the lumen 2,which is moved by the flow of the fluid 3 introduced into the lumen 2.According to the second embodiment, the rotary guide member 80 isconfigured to rotate the capsule body 60 with the flow of the fluid 3about an axis S passing through the gravity center G of the capsule body60 and substantially perpendicular to the longitudinal axis L in acircumferential direction. The rotary guide member 80 is composed ofprojections 81, 82 in a pocket form having openings 81 a, 82 a on theouter surface of the capsule body 60 to form a pair of one-way resistiveelements. The openings 81 a, 82 a are opened along the longitudinalaxial direction and toward the center portion of the capsule body 60.These pocket projections 81, 82 are disposed at a position off thecenter of the longitudinal axis L on the outer surface of the capsulebody 60 so as to be point symmetric with respect to the gravity center Gof the capsule body 60. Further, these pocket projections 81, 82 areformed symmetrically when they are divided into two pieces at a planeface including the longitudinal axis L of the capsule body 60 anddisposed to be point symmetric with respect to the gravity center G ofthe capsule body 60. Here, the pocket projections 81, 82 work asresistive elements and generate reaction force when the openings 81 a,82 a are opened toward upstream to face to the flow of the fluid 3, and,on the other hand, the pocket projections 81, 82 do not work asresistive elements when the openings 81 a, 82 a are opened towarddownstream and does not face to the flow of the fluid 3 and havedirectionality to generate reaction force to the flow of the fluid 3.

Next, an observation of inside of the lumen 2, for example, the largeintestine with the use of the capsule endoscope 50 of the secondembodiment will be described. Basically, the capsule endoscope 50 andthe fluid 3 are swallowed from a mouth to substantially fill the lumen 2such as the large intestine as an observed portion in the subject 1 withthe fluid 3 so that the capsule endoscope 50 travels as floating in thefluid 3 while an imaging member 71 takes images of the inside of thelumen 2. The capsule endoscope 50 and the liquid 3 may be swallowed atthe same time or may be swallowed in any order.

Here, as shown by arrows in FIG. 7A, the fluid 3 introduced in the lumen2 flows toward an exit of the lumen. When the capsule endoscope 50 is insuch a flow of the fluid 3, since the capsule body 60 has the rotaryguide member 80 of the pocket projections 81, 82 on its outer face, oneof the projection 81 or the projection 82 faces to the flow of the fluid3 to generate a reaction force. Accordingly, the capsule body 60 iscontrolled to move along the flow as rotating radially about an axis Sthat passes through the gravity center G of the capsule body 60 andsubstantially perpendicular to the longitudinal axis L.

For example, as shown in FIG. 7A, when the opening 81 a of theprojection 81 faces to the flow of the fluid 3, the projection 81generates an reaction force against the flow of the fluid 3 and works asa trigger to rotate the capsule body 60 in the clockwise direction aboutthe axis S. The capsule body 60 rotates in the clockwise direction aboutthe axis S (rolls forward) along the flow of the fluid 3, as shown inFIG. 7B. In this operation, the other projection 82 does not generate areaction force since the opening 82 a does not face to the flow. Then,when the capsule body 60 continues to rotate, as shown in FIG. 70C, theopening 82 a of the other projection 82 comes to face to the flow of thefluid 3 and the projection 82 generates a reaction force against theflow of the fluid 3 to rotate the capsule body 60 in the clockwisedirection about the axis S. With repeating this operation, the capsulebody 60 travels forwardly in the lumen 2 as rotating about the axis S bythe flow of the fluid 3.

The imaging member 71 takes images of the inside of the lumen 2 in sucha movement of the capsule body 60. In other words, the imaging member 71sequentially takes images of internal surfaces 2 a of the lumen 2 atfront side and back side of an axis of the lumen 2 that is the flowingdirection of the fluid 3 and at different directions from the flowingdirection of the fluid 3 as rotating forwardly and following therotating trajectory. With this structure, the entire area in the lumen 2and particular parts of the internal surface 2 a can be observed.

When the flow of the fluid 3 is small, since the resistance received bythe projection 81 or 82 facing to the flow becomes small, the capsulebody 60 does not rotate about the axis S. Accordingly, when the flow issmall, the imaging member 71 takes images in axial direction of thelumen 2 and, when the flow has certain strength or more, the imagingmember 71 observes particular portion of the internal surface 2 a. Whenthe flow of the fluid 3 has a periodicity, both entire images andpartial images can be observed more efficiently.

As described above, according to the capsule endoscope 50 of the secondembodiment, the capsule body 60 is moved as rotating radially about theaxis S (rotating forwardly) with the use of the flow of the fluid 3.With this structure, an observing field in the lumen 2 can dynamicallybe changed to be optimized even when the capsule endoscope 50 has astructure including a single observing member 70 for a direct view.Thus, the entire area in the lumen 2 can be surely observed withoutcomplicating the structure of an observing member (imaging member),which is to be installed in the capsule body 60. Further, according tothe capsule endoscope 50 of the second embodiment, the gravity center Gis set at the substantially center of the capsule body 60 and thespecific gravity with respect to the fluid 3 is set as substantiallyone. Accordingly, the capsule body 60 is in a mobile state and rotatablein the radial direction about the axis S smoothly when the pocketprojections 81, 82 constituting the rotary guide member 80 alternatelyface to the flow of the fluid 3. With this structure, the abovedescribed observing operation can certainly be performed.

FIG. 8 is a schematic block diagram showing a use example of a capsuleendoscope according to a third modification. A capsule endoscope 51 ofthe third modification has a pair of pocket projections 81, 82constituting a rotary guide member 80 in which openings 81 a, 82 a areopened toward ends along the longitudinal axial direction. With thecapsule endoscope 51 having the structure described in the thirdmodification, operations and effects same as those of the secondembodiment can be obtained.

FIG. 9 is a schematic block diagram showing a use example of a capsuleendoscope according to a fourth modification. A capsule endoscope 52 ofthe fourth modification includes an imaging member 71 as a firstobserving member and a second observing member 72 for forming at anotherimaging field in a longitudinal direction of the capsule body 60, whichis fixed another end of the capsule body 60. A compound-eye-typeobserving member 70 is composed of the first and second imaging members71, 72.

Here, similarly to the first imaging member 71, the second observingmember 72, which is not shown, includes a light source for illuminatingan imaging region, a solid-state imaging device such as CCD or CMOSimager for receiving catoptric light from the imaging region generatedby the illuminating light of the light source to image the inside of thelumen, and an imaging optical system such as an imaging lens forproducing an optical image of the imaging region to the solid-stateimaging device. Further, the first imaging member 71 is set to be a farfocus to focus on a entire image of the lumen 2 and the second imagingmember 72 is set to be a near focus to observe the internal surface orthe like of the lumen 2. Here, the capsule body 60 also includes amember having clearness or translucency for a region corresponding tothe imaging field of the second imaging member 72.

With the capsule endoscope 52 having the structure described in thefourth modification, operations and effects same as those of the secondembodiment can be obtained. Particularly, since the capsule endoscope 52of the third modification has a compound-eye-type structure with thefirst and second imaging members 71, 72 having different focusinglengths, when the capsule body 60 rotates radially about the axis S bythe flow of the fluid 3, the first and second imaging members 71, 72sequentially take images in the lumen 2 as following the rotatingtrajectory. In this case, since the focus position of the first imagingmember 71 is set at a long distance, a far focused and fine image of theinside of the entire lumen can be obtained by extracting a well-focusedimage from the obtained images. Further, since the focus position of thesecond imaging member 72 is set at a short distance, a near focused andfine internal surface image can be obtained and a particular portionsuch as a polyp can surely be observed by extracting a well-focusedimage from the obtained images.

FIG. 10 is a schematic block diagram showing a use example of a capsuleendoscope according to a fifth modification and FIG. 11 is a rear viewof the capsule endoscope. A capsule endoscope 53 of the fifthmodification includes a pair of grooves 83, 84 as a pair of one-wayresistive elements constituting a rotary guide member 80, as substitutesfor the pair of pocket projections 81, 82. The grooves 83, 84 are formedin a manner being opened near the end portions on the outer surface ofthe capsule body 60 along the longitudinal axial direction and towardthe side of the end portions. Inner walls of the grooves 83, 84 work asfluid contact faces 83 a, 84 b. The grooves 83, 84 are arranged to bepoint symmetric with respect to the gravity center G of the capsule body60. Further, the cross-sectional shape of the grooves 83, 84 may betriangular or U-shaped which are symmetrical when they are divided intotwo at a flat face including the longitudinal axis L of the capsule body60 and arranged to be point symmetric with respect to the gravity centerG.

Here, the grooves 83, 84 work as resistive elements to generate areaction force when the fluid contact faces 83 a, 84 a face toward theupstream and face to the flow of the fluid 3, and the grooves 83, 84 donot work as resistive element when the fluid contact face 83 a, 84 aface toward the downstream and do not face to the flow of the fluid 3and have directionality to generate reaction force to the flow of thefluid 3. With the capsule endoscope 53 having the structure described inthe fifth modification, operations and effects same as those of thesecond embodiment can be obtained.

FIG. 12 is a schematic block diagram showing a use example of a capsuleendoscope according to a sixth modification and FIG. 13 is a rear viewof the capsule endoscope. A capsule endoscope 54 of the sixthmodification includes a pair of holes 85, 86 as a pair of one-wayresistive elements constituting a rotary guide member 80, as substitutesfor the pair of pocket projections 81, 82. The holes 85, 86 are formedin a manner opened near the end portions on the outer surface of thecapsule body 60 along the longitudinal axial direction and toward theside of the end portions. The holes. 85, 86 are arranged to be pointsymmetric with respect to the gravity center G of the capsule body 60.Further, the cross-sectional shape of the holes 85, 86 may be triangularor round shape, which are symmetrical when they are divided into two ata flat face including the longitudinal axis L of the capsule body 60,and arranged to be point symmetric with respect to the gravity center G.

Here, the holes 85, 86 work as resistive elements to generate a reactionforce when the openings opened toward the upstream and face to the flowof the fluid 3, and the holes 85, 86 do not work as resistive elementwhen the openings open toward the downstream and do not face to the flowof the fluid 3 and have directionality to generate reaction force to theflow of the fluid 3. With the capsule endoscope 54 having the structuredescribed in the sixth modification, operations and effects same asthose of the second embodiment can be obtained.

Here, according to the third to sixth modifications of the secondembodiment, the rotary guide member 80 is composed of a pair of one-wayresistive elements formed by the pair of the pocket projections 81, 82,grooves 83, 84, or holes 85, 86. However, the rotary guide member 80composed of a pair of one-way resistive elements in which a plurality ofprojections, grooves, or holes are symmetrically disposed in combinationin each side may be employed.

Further, the projected resistive element may be openable and closable(projected and retracted) with respect to the outer surface of thecapsule body. In other words, when the fluid 3 is still (or its flow issmall), the resistive element is closed (installed in the capsule body)and when a large flow is generated, the resistive element is opened(projected) corresponding to the flow. With this structure, sinceprojections are projected only when they are need, the capsule endoscopecan be easily swallowed by the subject 1.

FIGS. 14A to 14C are schematic block diagrams showing a capsuleendoscope according to a seventh modification. A capsule endoscope 55 ofthe seventh modification includes a weight 91 installed in the capsulebody 60 and a slide space 92 for sliding the position of the weight 91in the longitudinal axial direction of the capsule body 60. Here, theweight 91 slides in the slide space 92 due to the flow of the fluid 3 tothe capsule body 60 so that the position of the gravity center of thecapsule body 60 is changed.

When the capsule endoscope 55 having such a structure is introduced inthe lumen 2 and stays in the fluid 3, for example, the weight 91 islocated at a position one-sided in the slide space 92, as shown in FIG.14A, and the capsule endoscope 55 flows in the fluid 3 in a manner ofbeing tilted due to the position of the gravity center, as shown in FIG.14A. When the flow of the fluid 3 works on the capsule body 60 in such acondition, the capsule body 60 rotates forwardly to be a substantiallyhorizontal state, as shown in FIG. 14B. With such movement of thecapsule body 60, the weight 91 slides to the center of the slide space92 and further moves to the other end of the slide space 92. Accordingto the dynamical changes of the position of the gravity center, thecapsule body 60 moves to continue the rotation, as shown in FIG. 14C. Byrepeating this operation, the capsule body 60 travels in the lumen 2 dueto the flow of the fluid 3 as rotating forwardly. Accordingly, with thecapsule endoscope 55 having the structure described in the seventhmodification, operations and effects same as those of the secondembodiment can be obtained.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A capsule medical apparatus comprising: a capsule body to beintroduced into a lumen of a subject; a control member controlling amovement of the capsule body in the lumen by a flow of a fluidintroduced in the lumen; and an observing member fixed inside thecapsule body and observing a direction of the flow of the fluid and adirection different from the flow of the fluid according to the movementof the capsule body.
 2. The capsule medical apparatus according to claim1, wherein the control member is a rotary guide member which rotates thecapsule body by the flow of the fluid in a circumferential directionabout a longitudinal axis of the capsule body.
 3. The capsule medicalapparatus according to claim 2, wherein the rotary guide member includesa spiral member provided on an outer surface of the capsule body so asto interfere the flow of the fluid.
 4. The capsule medical apparatusaccording to claim 3, wherein the spiral member is a spirally-formedprojection.
 5. The capsule medical apparatus according to claim 4,wherein the spirally-formed projection is a single continuousprojection.
 6. The capsule medical apparatus according to claim 4,wherein the spirally-formed projection includes a plurality ofdiscontinuous projections.
 7. The capsule medical apparatus according toclaim 1, wherein the observing member includes a first imaging memberforming an imaging field in a longitudinal direction of the capsule bodyand a second imaging member forming an imaging field in a directiondifferent from the direction of the imaging field of the first imagingmember.
 8. The capsule medical apparatus according to claim 7, whereinthe first imaging member has a far focus and the second observing memberhas a near focus.
 9. The capsule medical apparatus according to claim 7,wherein the second observing member has the imaging field oblique to thelongitudinal axial direction of the capsule body.
 10. The capsulemedical apparatus according to claim 7, wherein the second imagingmember has the imaging field perpendicular to the longitudinal axialdirection in the capsule body.
 11. The capsule medical apparatusaccording to claim 1, wherein the control member is a rotary guidemember which rotates the capsule body in a radial direction about anaxis passing through the gravity center of the capsule body andperpendicular to the longitudinal axis by the flow of the fluid.
 12. Thecapsule medical apparatus according to claim 11, wherein the rotaryguide member includes a pair of one-way resistive elements, theresistive elements having a same shape and being located on an outersurface of the capsule body to be point symmetric with respect to thegravity center of the capsule body, and the resistive elements havingdirectionality for generating a reaction force toward the flow of thefluid.
 13. The capsule medical apparatus according to claim 12, whereinthe one-way resistive elements are projections.
 14. The capsule medicalapparatus according to claim 13, wherein the projections can beprojected and retracted with respect to the outer surface of the capsulebody.
 15. The capsule medical apparatus according to claim 13, whereinthe projections are pocket projections each having an opening openedalong the longitudinal axial direction.
 16. The capsule medicalapparatus according to claim 12, wherein each of the one-way resistiveelements is a groove opened toward an end portion of the capsule bodyalong the longitudinal axial direction.
 17. The capsule medicalapparatus according to claim 12, wherein each of the one-way resistiveelements is a hole opened toward an end portion of the capsule bodyalong the longitudinal axial direction.
 18. The capsule medicalapparatus according to claim 11, wherein the observing member includesan imaging member which forms an imaging field in the longitudinal axialdirection of the capsule body.
 19. The capsule medical apparatusaccording to claim 11, wherein the observing member includes two imagingmembers each being respectively fixed at both end portions of thecapsule body in the longitudinal axial direction.
 20. The capsulemedical apparatus according to claim 19, wherein the imaging members area first imaging member and a second imaging member, respectively thefirst imaging member being fixed at an end of the capsule body in thelongitudinal axial direction and having a far focus, and the secondimaging member being fixed at another end of the capsule body in thelongitudinal axial direction and having a near focus.
 21. The capsulemedical apparatus according to claim 1, wherein the capsule body has aspecific gravity which is substantially one with respect to the fluidintroduced into the subject, and the gravity center of the capsule bodyis in a substantial center of the capsule body.
 22. A body-cavityobservation method, comprising the steps of: ingesting a capsule medicalapparatus; ingesting a fluid having a specific gravity which issubstantially same as that of the capsule medical apparatus; controllingthe capsule medical apparatus movement in a lumen, by a flow of thefluid; observing, by the capsule medical apparatus, a direction of theflow of the fluid; and observing, by the capsule medical apparatus, adirection different from the direction of the flow of the fluid.